fix(try_from_into): Rewrite exercise

Instead of working with strings, the exercise suggests creating a Color structure from other simple types (tuple, array, slice).

closes #392

exercises/conversions/try_from_into.rs

@@ -5,98 +5,100 @@
 use std::convert::{TryInto, TryFrom};
 
 #[derive(Debug)]
-struct Person {
-    name: String,
-    age: usize,
+struct Color {
+    red: u8,
+    green: u8,
+    blue: u8,
 }
 
 // I AM NOT DONE
-// Your task is to complete this implementation
-// in order for the line `let p = Person::try_from("Mark,20")` to compile
-// and return an Ok result of inner type Person.
-// Please note that you'll need to parse the age component into a `usize`
-// with something like `"4".parse::<usize>()`. The outcome of this needs to
-// be handled appropriately.
-//
-// Steps:
-// 1. If the length of the provided string is 0, then return an error
-// 2. Split the given string on the commas present in it
-// 3. Extract the first element from the split operation and use it as the name
-// 4. If the name is empty, then return an error.
-// 5. Extract the other element from the split operation and parse it into a `usize` as the age
-// If while parsing the age, something goes wrong, then return an error
-// Otherwise, then return a Result of a Person object
-impl TryFrom<&str> for Person {
+
+impl TryFrom<(i16, i16, i16)> for Color {
     type Error = String;
-    fn try_from(s: &str) -> Result<Self, Self::Error> {
+    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
+    }
+}
+
+impl TryFrom<[i16; 3]> for Color {
+    type Error = String;
+    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
+    }
+}
+
+impl TryFrom<&[i16]> for Color {
+    type Error = String;
+    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
     }
 }
 
 fn main() {
     // Use the `from` function
-    let p1 = Person::try_from("Mark,20");
-    // Since From is implemented for Person, we should be able to use Into
-    let p2: Result<Person, _> = "Gerald,70".try_into();
-    println!("{:?}", p1);
-    println!("{:?}", p2);
+    let c1 = Color::try_from((183, 65, 14));
+    println!("{:?}", c1);
+
+    // Since From is implemented for Color, we should be able to use Into
+    let c2: Result<Color, _> = [183, 65, 14].try_into();
+    println!("{:?}", c2);
+
+    let v = vec![183, 65, 14];
+    // With slice we should use `from` function
+    let c3 = Color::try_from(&v[..]);
+    println!("{:?}", c3);
+    // or take slice within round brackets
+    let c4: Result<Color, _> = (&v[..]).try_into();
+    println!("{:?}", c4);
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    #[test]
-    fn test_bad_convert() {
-        // Test that error is returned when bad string is provided
-        let p = Person::try_from("");
-        assert!(p.is_err());
-    }
-    #[test]
-    fn test_good_convert() {
-        // Test that "Mark,20" works
-        let p = Person::try_from("Mark,20");
-        assert!(p.is_ok());
-        let p = p.unwrap();
-        assert_eq!(p.name, "Mark");
-        assert_eq!(p.age, 20);
-    }
+
     #[test]
     #[should_panic]
-    fn test_panic_empty_input() {
-        let p: Person = "".try_into().unwrap();
+    fn test_bad_tuple() {
+        let _: Color = Color::try_from((-1, 0, 0)).unwrap();
     }
     #[test]
-    #[should_panic]
-    fn test_panic_bad_age() {
-        let p = Person::try_from("Mark,twenty").unwrap();
+    fn test_good_tuple() {
+        let c: Color = (183, 65, 14).try_into().unwrap();
+        assert_eq!(c.red, 183);
+        assert_eq!(c.green, 65);
+        assert_eq!(c.blue, 14);
     }
 
     #[test]
     #[should_panic]
-    fn test_missing_comma_and_age() {
-        let _: Person = "Mark".try_into().unwrap();
+    fn test_bad_array() {
+        let _: Color = [0, -1, 0].try_into().unwrap();
+    }
+    #[test]
+    fn test_good_array() {
+        let c: Color = [183, 65, 14].try_into().unwrap();
+
+        assert_eq!(c.red, 183);
+        assert_eq!(c.green, 65);
+        assert_eq!(c.blue, 14);
     }
 
     #[test]
     #[should_panic]
-    fn test_missing_age() {
-        let _: Person = "Mark,".try_into().unwrap();
+    fn test_bad_slice() {
+        let arr = [0, 0, -1];
+        let _ = Color::try_from(&arr[..]).unwrap();
     }
+    #[test]
+    fn test_good_slice() {
+        let v = vec![183, 65, 14];
+        let c = Color::try_from(&v[..]).unwrap();
 
+        assert_eq!(c.red, 183);
+        assert_eq!(c.green, 65);
+        assert_eq!(c.blue, 14);
+    }
     #[test]
     #[should_panic]
-    fn test_missing_name() {
-        let _ : Person = ",1".try_into().unwrap();
+    fn test_bad_slice_length() {
+        let v = vec![0, 0, 0, 0];
+        let _ = Color::try_from(&v[..]).unwrap();
     }
-
-    #[test]
-    #[should_panic]
-    fn test_missing_name_and_age() {
-        let _: Person = ",".try_into().unwrap();
-    }
-
-    #[test]
-    #[should_panic]
-    fn test_missing_name_and_invalid_age() {
-        let _: Person = ",one".try_into().unwrap();
-    }
-}
+}